My 2 year old DD has vomited once in the night for the past 3 nights out of four.
She has vomited just once at around the same time (1am, she goes to sleep at about 8pm).
After the second night I didn't give her any dairy for 24 hours thinking it could be a stomach bug, that night she didn't vomit. Day 4 I just fed her normally including dairy and last night she vomited again.
After I've cleaned her up she goes straight back to sleep and she only cries after she's been sick which makes me wonder if she has no pain or discomfort prior to vomiting.